What logbook? What is the logbook, you ask? Well, for aviators, the amount of hours flown is important, as it is the main indicator of their experience. So every pilot keeps track of his/her hours in a "logbook", which is basically a paper or electronic list of all flights that aviator flew. For flight simmers, this logbook is created and written to automatically every time you run one of the simulators mentioned above. Information like departure airport, destination airport and of course flight times are automatically logged.

I can edit the records inside Flight Simulator more or less, why should I need FS Logbook Editor? You are right, you can edit the records right in the flight simulator, but doing so feels a little clumsy to me, not much "user friendly". It works fine to change one or two things from time to time, but it is not much "joy" for some more detailed logbook management. One example is, say you want to keep only "serious" flights you did inside the logbook. This would require you to go through all the records and delete all "test", "tweak", "whatever tuning" flight records. If I would have to do all of this in flight simulator interface, I would rather not do it at all. And FS Logbook Editor can do more than just those simple edits.
Features:

Repair corrupted binary logbook files to some extent. (Flight Simulator X sometimes does not save logbook correctly and hangs due to this next time you start it. You can fix this with loading logbook into FS Logbook Editor and saving the logbook again without the need to delete the whole logbook)